AICP sent a survey to its members asking how they felt about an additional specialized certifcate in environmental planning OR transportation planning. This would be implemented in 2010.
Personally, I think it's a terrible idea. There is already enough pressure to maintain CM credits for AICP. I work in both types of planning in addition to having experience in about 7 other areas of planning. This topic has been discussed at great length on cyburbia. I also mentioned in the comment page that APA and AICP should listen to the concerns of planners on cyburbia, planetizen, and other sites before creating these certifcates. Greater emphasis should also be placed on licensure first.
This is another reason why I am not planning on staying in this profession that much longer. If planners made alot more money, I would be at least impartial to taking on more certifications. LEED is another area where there are increasing requirements just to stay accredited.